Diffusely adherent Escherichia coli strains isolated from children and adults constitute two different populations.

BACKGROUND: Diffusely adherent Escherichia coli (DAEC) have been considered a diarrheagenic category of E. coli for which several potential virulence factors have been described in the last few years. Despite this, epidemiological studies involving DAEC have shown inconsistent results. In this work, two different collections of DAEC possessing Afa/Dr genes, from children and adults, were studied regarding characteristics potentially associated to virulence. RESULTS: DAEC strains were recovered in similar frequencies from diarrheic and asymptomatic children, and more frequently from adults with diarrhea (P < 0.01) than from asymptomatic adults. Association with diarrhea (P < 0.05) was found for SAT-positive strains recovered from children and for curli-positive strains recovered from adults. Mixed biofilms involving DAEC and a Citrobacter freundii strain have shown an improved ability to form biofilms in relation to the monocultures. Control strains have shown a greater diversity of Afa/Dr adhesins and higher frequencies of cellulose, TTSS, biofilm formation and induction of IL-8 secretion than strains from cases of diarrhea in children. CONCLUSIONS: DAEC strains possessing Afa/Dr genes isolated from children and adults represent two different bacterial populations. DAEC strains carrying genes associated to virulence can be found as part of the normal microbiota present in asymptomatic children.

The circulation of human astrovirus genotypes in the Central West Region of Brazil.

Out of 1,588 faecal samples of children taken from three locations of the Central West Region of Brazil, 57 were positive for astroviruses (HAstVs) using reverse transcription-polymerase chain reaction (RT-PCR). They were genotyped by nested RT-PCR and/or genomic sequencing. HAstV-1 (42.8%), HAstV-2 (23.2%), HAstV-3 (3.6%), HAstV-4 (14.3%) and HAstVs -5, -6, -7 and -8 (1.8% each) were detected. In Goiânia and Campo Grande, HAstV-1 was the most frequently detected genotype while in Brasília (DF) it was HAstV-2. Shifts in the circulation of astrovirus genotypes were observed in DF and Campo Grande. All samples collected by rectal swabs were viral negative. The astrovirus genotypes were detected in all age groups and there was no correlation between genotype and age group.

The circulation of human astrovirus genotypes in the Central West Region of Brazil

Out of 1,588 faecal samples of children taken from three locations of the Central West Region of Brazil, 57 were positive for astroviruses (HAstVs) using reverse transcription-polymerase chain reaction (RT-PCR). They were genotyped by nested RT-PCR and/or genomic sequencing. HAstV-1 (42.8 percent), HAstV-2 (23.2 percent), HAstV-3 (3.6 percent), HAstV-4 (14.3 percent) and HAstVs -5, -6, -7 and -8 (1.8 percent each) were detected. In Goiânia and Campo Grande, HAstV-1 was the most frequently detected genotype while in Brasília (DF) it was HAstV-2. Shifts in the circulation of astrovirus genotypes were observed in DF and Campo Grande. All samples collected by rectal swabs were viral negative. The astrovirus genotypes were detected in all age groups and there was no correlation between genotype and age group.

Molecular characterization of VP6-encoding gene of group A human rotavirus samples from central west region of Brazil.

Group A rotaviruses are the main cause of acute gastroenteritis in children worldwide. The intermediate capsid protein VP6 encoded by segment 6 of the dsRNA genome is the major structural component of the virus and it is highly antigenic and immunogenic. VP6 is responsible for group and subgroup (SG) specificities, allowing classification of group A rotavirus into SG I, SG II, SG I + II, and SG non-I-non-II. VP6-encoding gene of 154 group A human rotavirus samples of different G and P genotypes recovered from children in three cities of Central West region of Brazil was amplified by reverse transcription-polymerase chain reaction followed by sequencing and phylogenetic analysis. Two distinct genetic groups could be recognized: VP6 genogroups I and II. Sequences analysis also revealed that all samples identified as VP6 genogroup I were associated with NSP4 genotype A, whereas samples identified as VP6 genogroup II were associated with NSP4 genotype B. This is the first study in Central West region regarding genetic variability of the VP6 gene. Further molecular surveillance of rotavirus strains is needed to understand better the occurrence of VP6 gene diversity in Brazil and the significance of VP6 for the control and prevention of rotavirus gastroenteritis.

Molecular characterization of the NSP4 gene of human group A rotavirus samples from the West Central region of Brazil.

Nonstructural protein 4 (NSP4), encoded by group A rotavirus genome segment 10, is a multifunctional protein and the first recognized virus-encoded enterotoxin. The NSP4 gene has been sequenced, and five distinct genetic groups have been described: genotypes A-E. NSP4 genotypes A, B, and C have been detected in humans. In this study, the NSP4-encoding gene of human rotavirus strains of different G and P genotypes collected from children between 1987 and 2003 in three cities of West Central region of Brazil was characterized. NSP4 gene of 153 rotavirus-positive fecal samples was amplified by reverse transcriptase-polymerase chain reaction and then sequenced. For phylogenetic analysis, NSP4 nucleotide sequences of these samples were compared to nucleotide sequences of reference strains available in GenBank. Two distinct NSP4 genotypes could be identified: 141 (92.2%) sequences clustered with NSP4 genotype B, and 12 sequences (7.8%) clustered with NSP4 genotype A. These results reinforce that further investigations are needed to assess the validity of NSP4 as a suitable target for epidemiologic surveillance of rotavirus infections and vaccine development.

Molecular characterization of the NSP4 gene of human group A rotavirus samples from the West Central region of Brazil

Nonstructural protein 4 (NSP4), encoded by group A rotavirus genome segment 10, is a multifunctional protein and the first recognized virus-encoded enterotoxin. The NSP4 gene has been sequenced, and five distinct genetic groups have been described: genotypes A-E. NSP4 genotypes A, B, and C have been detected in humans. In this study, the NSP4-encoding gene of human rotavirus strains of different G and P genotypes collected from children between 1987 and 2003 in three cities of West Central region of Brazil was characterized. NSP4 gene of 153 rotavirus-positive fecal samples was amplified by reverse transcriptase-polymerase chain reaction and then sequenced. For phylogenetic analysis, NSP4 nucleotide sequences of these samples were compared to nucleotide sequences of reference strains available in GenBank. Two distinct NSP4 genotypes could be identified: 141 (92.2 percent) sequences clustered with NSP4 genotype B, and 12 sequences (7.8 percent) clustered with NSP4 genotype A. These results reinforce that further investigations are needed to assess the validity of NSP4 as a suitable target for epidemiologic surveillance of rotavirus infections and vaccine development.

Astrovirus infection in children living in the Central West region of Brazil.

This study presents data regarding the circulation of astrovirus in Goiânia-GO and Brasília-DF. These viruses were detected in fecal samples from hospitalized children up to five years old with and without acute gastroenteritis. A total of 1244 fecal samples were collected in two periods, 1994 to 1996 (Brasília) and 1998 to 2002 (Goiânia and Brasília), and were analyzed for viral RNA using the reverse transcription-polymerase chain reaction (RT-PCR). Positivity rates of 4.3 and 0.5% for astrovirus were observed in children with acute gastroenteritis and those without gastroenteritis, respectively. Among children with gastroenteritis no statistically significant difference was seen with regards to viral positivity rates in relation to gender and age. However, a higher incidence rate was observed for children from Brasília aged 36 months or more. Overall, astroviruses occurred predominantly from September to March in the two cities, suggesting a seasonal pattern for these viruses which coincides with the highest relative air humidity period. The results of this study highlight the importance of astrovirus as an etiologic agent of acute gastroenteritis in children of the Central West region of Brazil.

Astrovirus infection in children living in the Central West region of Brazil

This study presents data regarding the circulation of astrovirus in Goiânia-GO and Brasília-DF. These viruses were detected in fecal samples from hospitalized children up to five years old with and without acute gastroenteritis. A total of 1244 fecal samples were collected in two periods, 1994 to 1996 (Brasília) and 1998 to 2002 (Goiânia and Brasília), and were analyzed for viral RNA using the reverse transcription-polymerase chain reaction (RT-PCR). Positivity rates of 4.3 and 0.5 percent for astrovirus were observed in children with acute gastroenteritis and those without gastroenteritis, respectively. Among children with gastroenteritis no statistically significant difference was seen with regards to viral positivity rates in relation to gender and age. However, a higher incidence rate was observed for children from Brasília aged 36 months or more. Overall, astroviruses occurred predominantly from September to March in the two cities, suggesting a seasonal pattern for these viruses which coincides with the highest relative air humidity period. The results of this study highlight the importance of astrovirus as an etiologic agent of acute gastroenteritis in children of the Central West region of Brazil.

Detection of calicivirus from fecal samples from children with acute gastroenteritis in the West Central region of Brazil.

The objective of this study was to describe the circulation of caliciviruses in the West Central region of Brazil and its correlation with children's gender and age, as well as with the year and months of the sample collection. Reverse transcriptase-polymerase chain reaction was performed to detect the human calicivirus genome in 1006 fecal samples that were collected in Goiânia (n = 696) and Brasília (n = 310). Viral RNA was detected in 8.6% of the samples. No significant difference in viral prevalence was found regarding gender, age or year of the sample. However, it was observed that in Goiânia, there is a higher incidence of caliciviruses from September to March. The analysis employing three primer pairs demonstrated that the Ni/E3 or JV12/13 primer pairs, which detect norovirus (NoV), detected 41 positive samples while the 289/290 primer pair, which detects NoV or sapovirus, detected the remaining 46 samples. Calicivirus circulates in the West Central region of Brazil and for better detection of this virus it is important to use more than one primer pair. Also, we conclude that the seasonality presented by this virus is related to higher humidity in the period.

Human milk glycoproteins inhibit the adherence of Salmonella typhimurium to HeLa cells.

The ability of human milk, as well as its protein fractions, to inhibit the adhesion and invasion of Salmonella typhimurium to HeLa cells was investigated. The results revealed that milk secretory immunoglobulin A (sIgA) inhibited neither the adherence nor the bacterial invasion; however, free secretory component and lactoferrin inhibited the bacterial adhesion and interacted with several bacterial proteins. Our data indicated that glycoproteins such as free secretory component and lactoferrin could act as protective compounds against infant enteric diseases, possibly binding to bacterial surface and blocking adhesion, the primordial step of S. typhimurium infection.

Detection of calicivirus from fecal samples from children with acute gastroenteritis in the West Central region of Brazil

The objective of this study was to describe the circulation of caliciviruses in the West Central region of Brazil and its correlation with children's gender and age, as well as with the year and months of the sample collection. Reverse transcriptase-polymerase chain reaction was performed to detect the human calicivirus genome in 1006 fecal samples that were collected in Goiânia (n = 696) and Brasília (n = 310). Viral RNA was detected in 8.6 percent of the samples. No significant difference in viral prevalence was found regarding gender, age or year of the sample. However, it was observed that in Goiânia, there is a higher incidence of caliciviruses from September to March. The analysis employing three primer pairs demonstrated that the Ni/E3 or JV12/13 primer pairs, which detect norovirus (NoV), detected 41 positive samples while the 289/290 primer pair, which detects NoV or sapovirus, detected the remaining 46 samples. Calicivirus circulates in the West Central region of Brazil and for better detection of this virus it is important to use more than one primer pair. Also, we conclude that the seasonality presented by this virus is related to higher humidity in the period.

In vitro adhesion and invasion inhibition of Shigella dysenteriae, Shigella flexneri and Shigella sonnei clinical strains by human milk proteins.

BACKGROUND: Shigella is the etiological agent of shigellosis, a disease responsible for more than 500,000 deaths of children per year, in developing countries. These pathogens colonize the intestinal colon, invade, spreading to the other enterocytes. Breastfeeding plays a very important role in protecting infants from intestinal infections. Amongst milk compounds, glycosylated proteins prevent the adhesion of many enteropathogens in vitro. The aim of this work was to determine the effect of human milk proteins on the colonization potential of Shigella dysenteriae, S. flexneri and S. sonnei. To fulfill this purpose, pooled milk samples from five donors, were fractionated by gel filtration and affinity chromatography. Using tissue culture, the milk fractions obtained were tested in Shigella adhesion and invasion assays. RESULTS: Our revealed showed that both adhesion and invasion of Shigella species were inhibited by low concentration of secretory immunoglobulin A, lactoferrin and free secretory component. This work also showed that, these proteins bind to superficial and whole-cell Shigella proteins. CONCLUSIONS: Our findings suggest that human milk may act inhibiting adhesion and, consequently, invasion of Shigella, thereafter preventing shigellosis in infants.

Avaliaçäo da terapia de reidrataçäo oral (TRO) com soluçäo de 90 miliequivalentes de sódio por litro em crianças de Manaus / Evaluation of oral rehydration with solution of 90 miliequivalent of sodium per litre in children of Manaus

O presente trabalho testou a eficácia e a tolerabilidade de uma soluçäo hidroeletrolítica glicosada, com 90 mEq de sódio por litro, em 25 crianças de uma comunidade pobre de Manaus-AM. Descreve-se a metodologia e as características da amostra estudada. Os resultados da TRO, a nível domiciliar, mostraram que 84% das crianças estavam adequadamente reidratadas em 5 horas de administraçäo da soluçäo e 100% em 24 horas. Todas as crianças aceitaram bem a soluçäo oral, näo tendo sido verificada qualquer reaçäo adversa à mesma. Os resultados säo muito satisfatórios, considerando-se o baixo nível sócio-econômico e a alta incidência de analfabetismo materno presente no bairro periférico deste estudo. Considera-se importante o uso persistente do hidratante oral, a orientaçäo de realimentaçäo precoce das crianças com sua dieta habitual, evitando-se assim pausas alimentares prolongadas ou alimentos inadequados e deletérios para as necessidades nutricionais dessas comunidades

Etiologia das diarréias agudas em Manaus: observaçöes ambulatoriais e na comunidade / Etiology of acute diarrheia in Manaus: observations in the outpatient clinics and in the community

Enteropatógenos foram investigados em 309 amostras de fezes diarréicas, de crianças de zero a seis anos de idade: 109 coletadas em ambulatório e 200 obtidas através de visitas domiciliares à comunidades péri-urbanas de Manaus. A mais alta incidência de diarréia foi observada na faixa etária de zero a 5 meses de idade, tanto em ambulatório como na comunidade. Os enteropatógenos mais frequentemente isolados foram Shigella sp. nos casos ambulatoriais e Escherichia coli enterotoxigênica, na comunidade